Ester-C Vitamin C, Immune Support Tablets, 1000 Mg, 120 Ct

1000 or thousand may refer to:

• 1000 (number), a natural number
• AD 1000, a leap year in the Julian calendar
• 1000 BC, a year of the Before Christ era
• 1000 metres, a middle-distance running event
• 1000°, a German electronic dance music magazine
• Thousand (comics), a Marvel Comics character
• "Thousand" (song), a song by Moby
• The Thousand (I Mille), the volunteers in the Expedition of the Thousand, a military action of the Italian Risorgimento, 1860

120 may refer to:

• 120 (number), the number
• AD 120, a year in the 2nd century AD
• 120 BC, a year in the 2nd century BC
• 120 film, a film format for still photography
• 120 (film), a 2008 film
• 120 (MBTA bus), a Massachusettes Bay Transport Authority bus route
• 120 (New Jersey bus), a New Jersey Transit bus route
• 120 (Kent) Construction Regiment, Royal Engineers
• 120 volts, standard electrical mains voltage in several countries in the Americas
• Lenovo IdeaPad 120, a discontinued brand of notebook computers
• Ching Chung stop (MTR digital station code 120), a Light Rail stop in Tuen Mun, Hong Kong
• 120 Lachesis, a main-belt asteroid
• Škoda 120, a compact sedan

1/20 may refer to:

• January 20 (month-day date notation)

C, or c, is the third letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is cee (pronounced ), plural cees.

In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (R′). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC.

Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods.

Esters can be formed from oxoacids (e.g. esters of acetic acid, carbonic acid, sulfuric acid, phosphoric acid, nitric acid, xanthic acid), but also from acids that do not contain oxygen (e.g. esters of thiocyanic acid and trithiocarbonic acid). An example of an ester formation is the substitution reaction between a carboxylic acid (R−C(=O)−OH) and an alcohol (R'−OH), forming an ester (R−C(=O)−O−R'), where R stands for any group (typically hydrogen or organyl) and R′ stands for organyl group.

Organyl esters of carboxylic acids typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. They perform as high-grade solvents for a broad array of plastics, plasticizers, resins, and lacquers, and are one of the largest classes of synthetic lubricants on the commercial market. Polyesters are important plastics, with monomers linked by ester moieties. Esters of phosphoric acid form the backbone of DNA molecules. Esters of nitric acid, such as nitroglycerin, are known for their explosive properties.

There are compounds in which an acidic hydrogen of acids mentioned in this article are not replaced by an organyl, but by some other group. According to some authors, those compounds are esters as well, especially when the first carbon atom of the organyl group replacing acidic hydrogen, is replaced by another atom from the group 14 elements (Si, Ge, Sn, Pb); for example, according to them, trimethylstannyl acetate (or trimethyltin acetate) CH₃COOSn(CH₃)₃ is a trimethylstannyl ester of acetic acid, and dibutyltin dilaurate (CH₃(CH₂)₁₀COO)₂Sn((CH₂)₃CH₃)₂ is a dibutylstannylene ester of lauric acid, and the Phillips catalyst CrO₂(OSi(OCH₃)₃)₂ is a trimethoxysilyl ester of chromic acid (H₂CrO₄).

Vitamins are organic molecules (or a set of closely related molecules called vitamers) that are essential to an organism in small quantities for proper metabolic function. Essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through the diet. For example, vitamin C can be synthesized by some species but not by others; it is not considered a vitamin in the first instance but is in the second. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols.

The term vitamin does not include the three other groups of essential nutrients: minerals, essential fatty acids, and essential amino acids.

Major health organizations list thirteen vitamins:

• Vitamin A (all-trans-retinols, all-trans-retinyl-esters, as well as all-trans-β-carotene and other provitamin A carotenoids)
• Vitamin B₁ (thiamine)
• Vitamin B₂ (riboflavin)
• Vitamin B₃ (niacin)
• Vitamin B₅ (pantothenic acid)
• Vitamin B₆ (pyridoxine)
• Vitamin B₇ (biotin)
• Vitamin B₉ (folic acid and folates)
• Vitamin B₁₂ (cobalamins)
• Vitamin C (ascorbic acid and ascorbates)
• Vitamin D (calciferols)
• Vitamin E (tocopherols and tocotrienols)
• Vitamin K (phylloquinones, menaquinones, and menadiones)

Some sources include a fourteenth, choline.

Vitamins have diverse biochemical functions. Vitamin A acts as a regulator of cell and tissue growth and differentiation. Vitamin D provides a hormone-like function, regulating mineral metabolism for bones and other organs. The B complex vitamins function as enzyme cofactors (coenzymes) or the precursors for them. Vitamins C and E function as antioxidants. Both deficient and excess intake of a vitamin can potentially cause clinically significant illness, although excess intake of water-soluble vitamins is less likely to do so.

All the vitamins were discovered between 1913 and 1948. Historically, when intake of vitamins from diet was lacking, the results were vitamin deficiency diseases. Then, starting in 1935, commercially produced tablets of yeast-extract vitamin B complex and semi-synthetic vitamin C became available. This was followed in the 1950s by the mass production and marketing of vitamin supplements, including multivitamins, to prevent vitamin deficiencies in the general population. Governments have mandated the addition of some vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. Recommendations for folic acid supplementation during pregnancy reduced risk of infant neural tube defects.